title: The phase diagram of the Heisenberg antiferromagnet with four-spin interactions.
abstract: We study the quantum phase diagram of the Heisenberg planar antiferromagnet with a subset of four-spin ring exchange interactions, using the recently proposed hierarchical mean-field approach. By identifying relevant degrees of freedom, we are able to use a single variational ansatz to map the entire phase diagram of the model and uncover the nature of its various phases. It is shown that there exists a transition between a Néel state and a quantum paramagnetic phase, characterized by broken translational invariance. The non-magnetic phase preserves the lattice rotational symmetry, and has a correlated plaquette nature. Our results also suggest that this phase transition can be properly described within the Landau paradigm.
authors.affiliation: Department of Physics, Indiana University, Bloomington, IN 47405, USA.
authors.forename: L
authors.initials: L
authors.lastname: Isaev
authors.forename: G
authors.initials: G
authors.lastname: Ortiz
authors.forename: J
authors.initials: J
authors.lastname: Dukelsky